Is it possible to mount a shock bar under the bed to mount longer shocks and gain more travel?? I have Deaver leaf springs (8 pack) and think the shocks limit my travel. Would I gain more if I mounted a shock bar up against the bed underneath without cutting the bed up? Or would it even do anything. Does anyone know? I thought I had seen this done somewhere online but can't find it again. Thanks

It's been done plenty of times on older trucks.
People normally mount them in a / \ type position. The more angle you have in them, the less effective they are in dampening the suspension. So if you drive the truck on-road, keep that in mind.

Getting more down travel in the suspension will ultimately mean other things will need changed to accomodate that travel...brake lines and even a longer slip yoke in the driveshaft (or it'll pull out).